macbook air acting really funny after spill into keyboard

Somebody spilled a juice type drink into the macbook air while the machine was out on loan. I don't know quite what it was, or how they mopped it up. I assume they didn't put it upside down afterwards. The juice-type drink went in the top right of the machine.

It's now got a bunch of dead keys on the top right hand side of the keyboard, which isn't the most expensive repair. Either a new palmrest assembly or a bunch of mucking around with replacing just the keyboard with some salvaged or OEM item off ebay.

However, there is a more worrying issue. The fan now spins up to maximum on the boot screen, and there are other issues to do with the machine, particularly system processes constantly sitting on between 70 and 100%, disappearing mouse pointer etc.

Last time I saw that sort of CPU-drain issue was on a G417 inch, and when I took it apart I discovered to my amazement that there were various loose screws and shattered pieces of ferrite sitting on the logic board, rattling about in there & creating short circuits. I'm amazed it even ran at all. Belonged to a colleague who'd had some dodgy guy in Hong Kong do a bunch of repairs on it after a serious dropping incident. Once the machine was back together properly, it ran fine.

So I am suspecting that in this case there is some form of semi-conductive residue on the logic board.

Has anybody met this before? Do you suppose that I should open her up, see which areas of the board are lit up by the moisture-sensitive markings, and clean those areas of the board down with isopropyl alcohol? Or do you suppose the machine is toast, and will require a new logic board as well as a new battery?